/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xalan.templates;

import javax.xml.transform.TransformerException;

import wx.xml.xalan.xalan.transformer.TransformerImpl;
import wx.xml.xalan.xpath.XPath;
import wx.xml.xalan.xpath.XPathContext;
import wx.xml.xalan.xpath.objects.XObject;

/**
 * Implement xsl:if.
 * <pre>
 * <!ELEMENT xsl:if %template;>
 * <!ATTLIST xsl:if
 *   test %expr; #REQUIRED
 *   %space-att;
 * >
 * </pre>
 *
 * @xsl.usage advanced
 * @see <a href="http://www.w3.org/TR/xslt#section-Conditional-Processing-with-xsl:if">XXX in XSLT Specification</a>
 */
public class ElemIf extends ElemTemplateElement {
    static final long serialVersionUID = 2158774632427453022L;

    /**
     * The xsl:if element must have a test attribute, which specifies an expression.
     *
     * @serial
     */
    private XPath m_test = null;

    /**
     * Get the "test" attribute.
     * The xsl:if element must have a test attribute, which specifies an expression.
     *
     * @return the "test" attribute for this element.
     */
    public XPath getTest() {
        return m_test;
    }

    /**
     * Set the "test" attribute.
     * The xsl:if element must have a test attribute, which specifies an expression.
     *
     * @param v test attribute to set
     */
    public void setTest(XPath v) {
        m_test = v;
    }

    /**
     * This function is called after everything else has been
     * recomposed, and allows the template to set remaining
     * values that may be based on some other property that
     * depends on recomposition.
     *
     * @param sroot The root stylesheet.
     * @throws TransformerException
     */
    public void compose(StylesheetRoot sroot) throws TransformerException {

        super.compose(sroot);

        java.util.Vector vnames = sroot.getComposeState().getVariableNames();

        if (null != m_test)
            m_test.fixupVariables(vnames, sroot.getComposeState().getGlobalsSize());
    }

    /**
     * Get an int constant identifying the type of element.
     *
     * @return The token ID for this element
     * @see wx.xml.xalan.xalan.templates.Constants
     */
    public int getXSLToken() {
        return Constants.ELEMNAME_IF;
    }

    /**
     * Return the node name.
     *
     * @return the element's name
     */
    public String getNodeName() {
        return Constants.ELEMNAME_IF_STRING;
    }

    /**
     * Conditionally execute a sub-template.
     * The expression is evaluated and the resulting object is converted
     * to a boolean as if by a call to the boolean function. If the result
     * is true, then the content template is instantiated; otherwise, nothing
     * is created.
     *
     * @param transformer non-null reference to the the current transform-time state.
     * @throws TransformerException
     */
    public void execute(TransformerImpl transformer) throws TransformerException {

        XPathContext xctxt      = transformer.getXPathContext();
        int          sourceNode = xctxt.getCurrentNode();

        if (transformer.getDebug()) {
            XObject test = m_test.execute(xctxt, sourceNode, this);

            if (transformer.getDebug())
                transformer.getTraceManager().fireSelectedEvent(sourceNode, this,
                    "test", m_test, test);

            // xsl:for-each now fires one trace event + one for every
            // iteration; changing xsl:if to fire one regardless of true/false

            if (transformer.getDebug())
                transformer.getTraceManager().fireTraceEvent(this);

            if (test.bool()) {
                transformer.executeChildTemplates(this, true);
            }

            if (transformer.getDebug())
                transformer.getTraceManager().fireTraceEndEvent(this);

            // I don't think we want this.  -sb
            //  if (transformer.getDebug())
            //    transformer.getTraceManager().fireSelectedEvent(sourceNode, this,
            //            "endTest", m_test, test);
        } else if (m_test.bool(xctxt, sourceNode, this)) {
            transformer.executeChildTemplates(this, true);
        }

    }

    /**
     * Call the children visitors.
     *
     * @param visitor The visitor whose appropriate method will be called.
     */
    protected void callChildVisitors(XSLTVisitor visitor, boolean callAttrs) {
        if (callAttrs)
            m_test.getExpression().callVisitors(m_test, visitor);
        super.callChildVisitors(visitor, callAttrs);
    }

}
